New shapeshifting medical microbots inspired by germs

Nanobots have been a hot topic within the miniaturization trend for a long time. Developments in the medical robotics field ranging from tiny experimental robots that can swim through the bloodstream to origami-like creations designed to be swallowed. But one of the more troublesome problems is figuring out how to control microbots once they’re released. That’s where Selman Sakar, Hen-Wei Huang and Bradley Nelson come in. These researchers have invented a new type of microbot that might be the beginning of a revolution in how we deliver medication to the body.

The trio of researchers is working on microbots that can move about, and can also be produced quickly and in quantity. The prototypes they describe in this Nature Communications report are soft, flexible and motorless. Inspired by the shapes of actual microbes, particularly the mighty morphin’ Trypanosoma brucei, (one of the parasitic protozoans that causes African sleeping sickness), the microbots take the shape of either flat heads and helical tails, or just straight-up tiny helices. They’re made using biocompatible polymers and hydrogels, and good old iron (III) oxide to make them magnetically responsive. And the result is a 500μm-wide creation that can be controlled using an electromagnetic field, capable of altering its shape in response to the temperature of its surroundings.

Selman Sakar at EPFL and Hen-Wei Huang and Bradley Nelson at ETHZ are developing and testing a number of configurations of microbots that can not only move about, but can be produced quickly and in quantity using a new manufacturing technique. The result is a robot that can be controlled using an electromagnetic field — switching the direction of the field could steer the robots through their fluid bath. When the flock of microbots gets to its destination, the bots can alter their shape in response to temperature — in this case, the researchers used lasers of particular non-ionizing wavelengths. At 40°C, which is about the temperature of a wicked fever, the microbots’ elastic modulus changes and they lay themselves out flat, exposing their hydrophilic insides to the bloodstream.

This class of medical microbots could be useful for everything from drug delivery to microsurgery, clearing out clogged arteries and the like. Research into microbots has been driven by a number of factors, including the ability to deliver highly targeted treatments to specific areas of the body and the ability to perform certain types of repair or treatment without causing additional trauma.

One of the challenges of chemotherapy, for example, is the difficulty of delivering anti-cancer drugs directly to the cancerous growth without impacting surrounding healthy tissue. Chemotherapy is often bluntly described as a series of treatments designed to kill cancer at least slightly faster than the rest of the patient — and one of the problems with many anti-cancer drugs is that at the high doses required to kill a significant percentage of cancer cells kill a great many normal cells as well. Targeted, location-specific therapy works well for certain cancers, but this assumes that the growth or tissue can be isolated and that the treatment can be localized. Cancer is a many-headed hydra with far too many heads to be cured by any single treatment — but the ability to deliver targeted drug regimens to specific locations could significantly improve mortality rates for certain types of cancer.